Japan's Defense Ministry says a Chinese intelligence-gathering vessel has entered the East China Sea, completing a voyage around the Japanese archipelago.

Japan's Maritime Self-Defense Force confirmed the Chinese navy ship sailing southwest in the Pacific about 70 kilometers northeast of Tanegashima Island, Kagoshima Prefecture, around 2 p.m. Saturday.

It then entered the East China Sea, following a passage through the Osumi Strait on Sunday, capping a roughly half-month voyage around the Japanese archipelago.

The vessel entered the Sea of Japan from the East China Sea via the Tsushima Strait on March 28. It passed through the Tsugaru Strait in northern Japan to enter the Pacific.

The ship then traveled south, passing through the contiguous zone near the Izu Islands, just outside Japan's territorial waters, on April 10.

Defense Ministry officials are keeping an eye out for the vessel. A similar voyage by a Chinese navy intelligence-gathering ship was spotted from June through July of last year as well.